Morning EMH at the magic kingdom
I've done both the a.m. and p.m. EMH and I f ind the mornings to be less crowded. I think this is because people tend to stay out late and don't want to get up early. Also, many people do character breakfasts or regular breakfasts or even have to get the little ones up and dressed. The p.m. EMH can have wait times just as long as during the day.
One tip i can offer is that if you're going to the a.m. EMH at the MK, try to get in even before the gates open. Last time I was there, in Aug., we walked straight through one opened turnstyle which was opened only for the Cinderella Castle character breakfast guests and special guided tours. No one stopped us and we weren't going to either. We had Main St. all to ourselves and just waited until the rest of the park opened. By then, we were miles ahead of everyone else and were first on Space mtn.